Superheater boiler and method of operating the same



Patented Jan. 23, 1934 UNITED STATES SUPERHEATER BOILER AND METHOD OFOPERATING THE SAME Ralph M. Hardgrove, Bethlehem, Pa., assignor to TheBabcock & Wilcox Company, Bayonne, N. J., a corporation of New JerseyApplication November 4, 1930. Serial No. 493,260

2 Claims.

This invention is concerned with a protector operating during abnormalconditions arising in the use of steam generators of the high heatrelease type.

A specific object of the invention is the protection of superheatersunder abnormal conditions which are contrasted with conditions underwhich such superheaters protect themselves.

A further object of the invention is to provide such protection bymixing cool gases with the hot furnace gases of a high heat release typeinstallation at times when needed and stopping the supply of cool gaseswhen the boiler is operating normally.

Other objects of the invention will appear as the accompanyingdescription proceeds. V

In the accompanying drawing there is shown a figure illustrating steamgenerating equipment mainly in vertical section.

The illustrative apparatus comprises a boiler furnace 10 and a boilersection 12, the latter having downtake headers 14 connected by means ofwater tubes 16 to uptake headers 18. The water tubes are shown arrangedin two banks between which are superheater tubes 20. The superheatershown is an interdeck superheater having a lower header 22 and an upperheader 24, arranged with reference to the baffles 26, 28 and 30 asillustrated.

The downtake headers 14 are connected to the steam drum 32 by nipples34, and the boiler circulation is completed by circulating tubes 36connecting the headers 18 to the steam drum 32. A vertical bafiie 38separates the second and third passes of the boiler.

The superheater shown is in the first gas pass and is therefore subjectto the concentration of heat from the hot furnace gases. Under normaloperation the flow of steam through the superheater tubes causes suchheat abstraction from them that the superheater metal is protectedagainst overheating and the detrimental effects of such overheating.Under abnormal conditions, as when the boiler is starting up,circulation will start in the water tubes and they will be therebyprotected. Until steam is discharged from the boiler there is no flowthrough the superheater tubes 20. For this conditon they are disclosedas protected by a mixture of cold gases with the hot furnace gases.These cold gases enter the combustion chamber 10 through ports 40 and 42at one side of the combustion chamber and through ports 44 and 46 at theother side.

Because of the fact that the mixture of the large excess of cold gaswith the hot furnace gases makes it impossible to efficiently makesteam, or to superheat steam to the desired high temperature, thismixture cannot be used during normal boiler operation. Control of themixture is effected in the illustrative apparatus by means of regulators48 and 50 associated respectively with the ports 40 and 42, and otherregulators 52 and 54 on the other side of the furnace associatedrespectively with the ports 44 and 46.

The regulators herein shown are pivoted gates, the gates 48 and 50 beingconveniently operable by means of a rod 56 held in any desired positonby securing means 58. On the other side of the furnace the gates 52 and54 are operated by a similar rod 60 held by securing means 84.

The gates 48 and 50 are preferably located in the distributing header 62receiving its cold gas supply through a conduit 64. On the other side ofthe furnace a similar distributing header 66 and conduit 68 areprovided.

Inclination of the ports upwardly and inwardly promotes the developmentof a desirable mixture of gases. in the disclosure of the wall formingthe ports 40 and 42.

The combustion chamber illustrated is formed by water walls in which thetubes 70 are connected to upper and lower headers '72 and 74respectively on one side of the furnace. On the other side of thefurnace the water wall tubes 76 are connected to upper and lower headers78 and 80, respectively.

A fuel burner 82 is shown applied to one side of the furnace.

While the invention has been described with reference to the particularapparatus disclosed it is not limited thereto but is of a scopecommensurate with the scope of the subjoined claims.

What I claim as new, and desire to secure by Letters Patent, is: j

1. In a boiler having a. furnace, means for burning fuel in suspensionin said furnace, a steam generating section in the path of the heatinggases leaving said furnace, and a superheater associated with said steamgenerating section and in an initial portion of the flow path of theheating gases leaving said furnace, the method of protecting thesuperheater during starting-up periods which comprises introducing andintimately mixing a quantity of low temperature air with said heatinggases subsequent to a point where the fuel combustion has beensubstantially completed and before said heating gases contact with thesuperheater. 1

2. In a boiler having a furnace, means for burning fuel in suspensioninsaid furnace and steam superheating tubes in the initial portion of aconvection heated zone of said boiler above said furnace, the method ofpreventing overheating of thesuperheater tubes during starting-upperiods of said boiler which comprises tempering the heating gasesleaving said furnace with low temperature cooling air at a point beyondthe main combustion zone and below but adjacent to said superheatertubes.

RALPH M. HARDGROVE.

Such an arrangement is indicated

